Set-screw for lamp globes and shades.



N0. 808,290. PATENTE'D DEC. 26, 1905.

V T. G. LUSON. SET SCREW FOR LAMP GLOBES AND SHADES.

APPLICATION FILED MAR.28.1905

l W W/W UNITED STATES PATENT OFFIQE.

SET-SCREW FOR LAMP GLOB ES AND SHADES.

Specification of Letters Patent.

Patented Dec. 26, 1905.

Application filed March 28, 1905. Serial No. 252,567.

To aZZ whom it may concern.-

Be it known that I, THOMAS GERHARD LUSON, clerk, a subject of the Kingof Great Britain, and a resident of 1 Old Dover road, Blackheath,London, England, have invented a new and useful Improvement in Set-Screws for Lamp Globes and Shades, of which the following is aspecification.

Globes and shades for gas and other lamps are frequently secured inposition on their galleries or supports by means of setscrews. Thesescrews grip the edge or lip I of the lobe or shade more or less tightly.

The glo e being of glass is subject to considerable expansion andcontraction by reason of the variation in temperature caused by thelighting or extinguishing of the lamp. The set-screws, however, as atpresent used are not equally responsive to variations in temperature,and there is nothing to prevent them from being screwed too tight.Consequently, therefore, there is constant danger of undue pressure fromthe screws, which pressure is liable to cause the fracture of the globe.

According to my invention I provide setscrews so constructed that theycannot grip too tightly, but will press only elastically on the globe orshade and will yield to the glass in expansion or contraction as andwhen required.

In the accompanying drawings I have shown a set-screw constructedaccording to my invention.

Figure 1 is a longitudinal section through the screw, which is shownmuch larger than the size which will usually be employed. Fig. 2 showsit in position securing a gasglobe to a allery. Fig. 3 is a view similarto Fig. 1, showing the screw slightly differently made.

The screw comprises a hollow body a, externally threaded at one end toscrew into the gallery or support. Internally the body a is of twodiameters b and c, I) being the larger. Within the body a is a plunger(1, having a collar 6, which fits easily th larger end I) and is capableof sliding therein. The'plunger fits easily t e ELI O GI portion of thehollow screw-body, and its end, preferably rounded off, protrudes beyondth body a in the manner shown. At the back the hollow body a is closedby a screw-cap j, which may either be annular to permit the passage ofthe back end of the plunger a globe, as shown at Fig. 2, it is capableof yielding. In this manner the globe is held by an elastic grip, andhence the tendency to fracture the globe above referred to is' removed.

h is a shoulder on the screw, so placed as to prevent overscrewing,which might neutralize the advantages of the spring-seated plunger.I/Vhen, however, the form of screw shown in Figs. 1 and 2 is used, anytendency to bind the glass too tightly will be detected by the operatoropening the back end of the plunger protruding through the hole in thecapf.

What I claim as my invention, and desire to secure by Letters Patent, is

1. A removable set-screw for use in supporting a lamp globe or shadefrom a gallery, comprising a hollow body having a screwthreadedengagement with the gallery, a plunger sliding in the hollow body, acollar on the plunger, a cap screwed into the end of the hollow body anda spring interposed between the collar and cap, as and for the purposeset forth.

2. A removable set-screw for use in supporting a lamp globe or shadefrom a gallery, comprising a hollow body having an external threadthereon for engagement with the gallery, an exterior shoulder on thehollow body for preventing overscrewing of the same, a plunger slidingwithin the hollow body and a spring arran ed to yieldingly force theplunger outwardly as and for the purpose set forth.

3. A removable set-screw for use in sup porting a lamp globe or shadefrom a gallery, comprising a hollow body havin a screw threadedengagement with the gallery and a spring-actuated plunger sliding 1n thehollow body and arranged to protrude at either end thereof,substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

THOMAS GERHARD LUSON.

I/Vitnesses:

ALFRED S. BIsHoP, H. D. JAMESON.

